Extruder with a shaping device

ABSTRACT

The invention describes an extrusion system ( 1 ) with a shaping device ( 3 ), which has at least one calibrating device ( 9 ) comprising in particular a plurality of calibrating tools disposed in succession in the extrusion direction. The calibrating device ( 9 ) and/or the calibrating tools ( 24,31  to  33 ) are provided with cooling ducts ( 49 ) for passage of a heat treatment agent ( 50 ). The shaping device ( 3 ) has mould surfaces for application against an article ( 6 ) to be passed through. Furthermore, at least between an extrusion tool ( 8 ) of the shaping device ( 3 ) and the immediately succeeding calibrating tool in the extrusion direction and/or between the first calibrating tool ( 24 ) and at least one further calibrating tool ( 31,32,33 ), a seal device is disposed closing off the article ( 6 ) to be passed through in the region of its outer surfaces ( 48 ) from the environmental pressure, in order to form a cavity ( 38  to  41 ).

FIELD OF THE INVENTION

The invention relates to an extrusion system with a shaping device.

BACKGROUND OF THE INVENTION

Shaping devices are already known by means of which extruded articles,particularly hollow profiles or pipes, emerging from an extruder nozzle,are calibrated to desired outer and inner dimensions and are hardened atthe desired outer dimensions or, in order to obtain the desiredintrinsic rigidity, are cooled to the temperature provided for thatpurpose. Such shaping devices are known from the book by WalterMichaeli, Extrusions-werkzeuge für Kunststoffe und Kautschuk”, from CarlHanser Verlag, Munich/Vienna, second fully revised and expanded edition,published 1991, particularly pages 321 to 329. Shown on page 323 is anexternal calibration with vacuum, in which the extrudate emerging fromthe extrusion tool is introduced in the form of a hollow profile at somedistance after emergence from the nozzle lip of the extruder tool into acalibrating tool, by means of which the extrudate is passed through inthe area of its surrounding outer surface, in contact with the mouldsurfaces of the calibrating tool. The contact without clearance of thesurface of the extrudate on the individual mould surfaces of thecalibrating tool is achieved by air passages, particularly slots locatedin the mould surfaces, and which are connected by supply lines to avacuum source. In order to cool the extrudate, the calibrating tools areprovided with one or more surrounding ducts for a heat treatment agent,and the vacuum can increase in the individual air passages or slots asthe distance from the nozzle lip of the extruder tool increases. Thetemperature of the heat treating agent, in contrast to the masstemperature of the extruded profile, is extremely low and comes to about20° C. Connecting then to such so-called dry calibrators are usually oneor more cooling baths, in which the sufficiently rigid profiles, withpartial application of vacuum or wetting via spray nozzles or passagethrough water baths, are cooled to room temperature. In many casessufficient surface quality of the extrudates produced cannot be achievedwith such calibrating tools over a lengthy service life of the shapingdevice.

A further device for calibrating extruded profiles, particularlyextruded hollow profiles of thermoplastics, has become known from DE 2239 746 A, in which there is located at a spacing in the extrusiondirection behind the extruder tool or injection head of the plasticsworm extruder press, a vacuum calibrating device with a cooling deviceintegrated therein. In connection with the vacuum calibration devicethere is provided a low-pressure calibration tank through which acoolant flows, the vacuum calibrating device being so designed thattherein only the outer skin and any present outer profile portions suchas fine contours of the profile to be calibrated are shaped into theirfinal form. The residual heat still contained in the profile is removedby the coolant in the low pressure calibration tank. Located in thevacuum calibrating device are individual calibrating plates at a spacingfrom one another, which thus form cavities in the form of vacuum slots,through which the extruded article is suctioned with the aid of theapplied vacuum against the mould surfaces of the individual calibratingplates. In the calibration device proposed here, in all cases ofapplication perfect surface quality of the extruded article and a longservice life of a device could not be achieved.

SUMMARY OF THE INVENTION

The object underlying the present invention is to achieve, even at highthroughputs, a perfect and constant surface quality of the extrudatesproduced, particularly of window profiles or pipes or the like, withoutincreasing the outlay on machinery.

This object of the invention is achieved by providing a shaping devicefor an extrusion system comprising an extrusion tool and a calibratingdevice having a plurality of calibrating tools arranged one afteranother along an extrusion direction in which an extruded article fromthe extrusion tool travels through the calibrating device, wherein aseal device is disposed between an end face of the extrusion tool and anupstream end face of the first calibrating tool, and between thedownstream end face of each calibrating tool and the upstream end faceof an immediately succeeding calibrating tool, the seal devices beingstructured and arranged to surround the outer surface of the extrudedarticle and to maintain a space in the extrusion direction between therespective end faces between which the seal device is disposed so as tocreate a cavity surrounding the extruded article that is closed off fromenvironmental pressure outside the calibrating device, whereby thecavity can be evacuated to a reduced pressure relative to theenvironmental pressure. The surprising advantage of this solutionresides in the fact that, simultaneously with a reduction in the outlayfor construction and servicing the calibrating tools, the surfacequality can be considerably increased, avoiding air passages or cavitiesfor application of vacuum to the profile in the calibrating tools. In away which could not be foreseen and was totally surprising to the personskilled in the art, in this way however higher dimensional exactitude ofthe extrudate could be achieved, as the extrudate, after emerging fromthe nozzle lip of the extruder tool, is no longer exposed toenvironmental conditions. By means of the direct transfer of theextrudate from the extruder tool into the calibrating tools, sinking ofthe outer peripheral surfaces by means of a web located there under orwithin the profile, is avoided, as the external air pressure cannotbecome directly effective on the outer surface. This however effects inan unforeseeable way rapid precipitation of lubricants or a condensationof lubricant residues, such for example as the waxes or the like mixedwith the raw materials, which, due to the high temperatures in thisarea, are still liquid. In this way the service life of such toolsbetween the individual cleaning procedures is considerably increasedwithout a disadvantageous alteration in surface quality, ascontamination in the inlet area of the calibrating tools is prevented byremoval of the superfluous lubricants, and contamination in the mouldsurfaces of the individual calibrating tools is avoided by theelimination of air passages in the predominant area of the mouldsurfaces of the calibrating tool.

In addition to the seal from external environmental conditions, vacuumor low pressure is applied directly to at least one of the cavities, andthe article is cooled immediately thereafter. In this way lubricantresidues and precipitated additives such as waxes can be directlyremoved by the applied vacuum, when adequate temperatures aremaintained. Thus the service life of such tools between the individualcleaning procedures is considerably increased without disadvantageousalteration in the surface quality, as contamination in the inlet area ofthe calibrating tools is prevented by the removal of superfluouslubricants, and contamination in the mould surfaces of the individualcalibrating tools is avoided by the elimination of air passages in thepredominating area of the mould surfaces of the calibrating tool.

By providing the cavities delimited by the end faces of the calibratingtools and the seal devices, vacuum slots in the mould surfaces can beomitted, whereby formation of smearing by the smooth continuous mouldsurfaces is avoided, and the respectively required polished effect canbe simply achieved on the surface of the article.

It is also advantageous to make the lengths of the mould surfaces in theextrusion direction at least seven times the distance between the nozzlelip of the extrusion tool and the first calibrating tool and thedistance between adjacent calibrating tools, as in this way hardening,shaping and smoothing of the surface of the article and an improvedquality and lower build-up of tension in said article can be achieved bythe gentle smooth cooling and guidance of the article.

By providing each of the cavities with its own line for evacuating thecavity, evacuation is achieved of the individual cavities, if necessaryalso with a differing degree of low pressure.

Advantageously, the first calibrating tool and the next succeedingcalibrating tool are connected to each other so as to permit relativemovement therebetween in the extrusion direction. This permits acontinuous length compensation by means of the relative movement of acalibrating tool, caused by differing extrusion speeds or extrusiontemperatures, so that faults in the article or in its surface can bereliably eliminated.

Furthermore, the processing costs, and above all also the volume of thecavities for applying the vacuum, can be reduced by the design accordingto the invention. In this way universal adaptation of the widthextending in the extrusion direction of the cavities serving as vacuumslots, is possible in a simple way. Adjustment of the width of thesecavities can be effected manually or automatically by displacement ofindividual calibrating tools relative to the calibrating table.

By forming the line for the cavity immediately succeeding the extrusiontool at least partially in the extrusion tool, a disturbance-freewithdrawal of additives or lubricants or the like, which are only liquidat higher temperatures, is made possible without these forming ablockage during extraction, thus blocking the line.

An improved surface quality or quality of the cover layer can beachieved by providing an inlet for supplying a flushing agent into thecavity immediately succeeding the extrusion tool, as residues oflubricants or additives adhering more strongly to the surface of the hotarticle, which is still plastic, can be perfectly removed and extracted.

By providing elastically deformable seal devices between the extrusiontool and the first calibrating tool and between adjacent calibratingtools, temperatures altering during operation and the thermal expansionscaused thereby can be compensated for without mechanical readjustment ofthe extrusion system.

A simple adaptation to differing spaces of the cavities and a vacuum ofvarying intensity applied in these cavities, can be achieved byconstructing the seal devices as inflatable seals that are pressurizedby a pressure supply system cooling of the surface layers or coatings ofthe article and thus a good dimensional stability are achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail in the following withreference to the embodiments given by way of example and shown in thedrawings, which show:

FIG. 1: an extrusion system with a shaping device according to theinvention in side view and in a simplified schematic illustration;

FIG. 2: the shaping device according to the invention in end view, incross-section along lines II—II in FIG. 1 and in a simplified schematicillustration;

FIG. 3: the shaping device according to FIG. 2 in side view, incross-section along lines III—III in FIG. 2;

FIG. 4: a further and if necessary independent embodiment of the shapingdevice according to FIG. 3 in side view, in cross-section and insimplified scheatic view;

FIG. 5: another and if necessary independent transition zone accordingto the invention between the extruding tool and the calibrating toolimmediately following it, in side view, in cross-section on a largerscale and in a schematic, simplified illustration;

FIG. 6: a further and if necessary independent transition zone accordingto the invention between the extruding tool and two calibrating toolsimmediately following in the extrusion direction, of another shapingdevice according to the invention, in side view, in cross-section on anenlarged scale and in a schematic, simplified illustration;

FIG. 7: another and if necessary independent variant construction of ashaping device according to the invention with air passages located inthe calibrating tools for connection to a vacuum source, in side viewand in section;

FIG. 8: a further and if necessary independent embodiment of a shapingdevice according to FIG. 7, in end view and in partial section along thelines VIII—VIII.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

It should be noted at the outset that in the various embodimentsdescribed identical parts are provided with identical reference numbersor identical component titles, the disclosures contained in the entiredescription being meaningfully capable of transfer to identical partswith identical reference numbers of identical component titles.Furthermore, individual ones from the various embodiments shown can inthemselves represent independent solutions according to the invention.

FIG. 1 shows an extrusion system 1, which consists of an extruder 2, ashaping device 3 following it, and following this a cooling device 4which can also if necessary represent a calibrating device, andfollowing this again a caterpillar pull-off 5 for an extruded article 6.The caterpillar pull-off 5 serves to draw off the article 6, for examplea profile of plastic for window construction, in the extrusiondirection, arrow 7, starting from the extruder 2, through the shapingdevice 3 and the cooling device 4. In this embodiment the shaping device3 consists of an extrusion tool 8, a calibrating device 9 andcalibrating plates 10 in the cooling device 4. The calibrating plates 10however can also serve purely as support plates for the article 6.

In the area of the extruder 2 there is located a storage container 11,in which there is stored a material 12 such for example as a plastic 13,which is passed to the extruder 2 by a conveyor worm 14. The extruder 2also comprises a plasticising unit 15, by means of which, during passageof the material 12 through it, by means of the conveyor worm 14, and ifnecessary additional heating devices 16, the material 12 in accordancewith its inherent properties, under pressure and if necessary theapplication of heat, is heated and plasticised and conveyed in thedirection of the extruder tool 8. Before entry into the extruder tool 8,the mass flow of plasticised material 12 is passed in transition zones17 to acquire the desired profile cross-section.

The extruder tool 8 with the plasticising unit 15 and the storagecontainer 11 are supported or secured on a machine bed 18, the machinebed 18 being mounted on a plane support surface 19, such for example asa factory floor.

The calibrating device 9 with the subsequent cooling device 4 is locatedor secured on a calibrating table 20, said calibrating table 20 beingsupported on rollers 21 on a rail 22 secured on the support surface 19.This mounting of the calibrating table 20 via the rollers 21 on the rail22 serves to enable the entire calibrating table 20 with the devices andarrangements located thereon, to be displaced in the extrusiondirection, arrow 7, towards or from the extruder tool 8. In order to beable to execute this displacement movement more simply and precisely,for example there is associated with one of the rollers 21 adisplacement drive 23, as indicated schematically in dotted lines, andwhich enables deliberate and controlled longitudinal movements of thecalibrating table 20 towards the extruder 2 or away from it. Anysolutions and units known from prior art can be used for drive andcontrol of the displacement drive 23.

As shown in FIGS. 2 to 4, in this embodiment the extruder tool 8 isimmediately followed by a calibrating tool 24 of the calibrating device9, the calibrating tool 24 being secured preferably in a floatingmanner, yet exactly accurate to axis on the devices or tools of thecalibrating device 9 to be described in more detail later, following thecalibrating tool 24 in the extrusion direction, arrow 7. The calibratingtool 24 is thus a component part of the calibrating device 9 and has endfaces 25, 26 aligned vertically to the extrusion direction, arrow 7. Inthis case the end face 25 is facing a nozzle lip 27 or end face of theextruder tool 8 and located at a distance 29 from the nozzle lip 27 bymeans of a preferably sealing spacer member 28. The end face 26 of thecalibrating tool 24, facing away from the extruder tool 8, follows via afurther spacer member 30, which can be of identical size or differentfrom the distance 29 between the end face 25 and the nozzle lip 27, ofone of the further calibrating tools 31 to 33 of the calibrating device9, in the extrusion direction, arrow 7. These further calibrating tools31 to 33 are located one behind the other respectively in the extrusiondirection, arrow 7, at intervals 34,35 and are secured on thecalibrating table 20. Between the individual calibrating tools 31 to 33,there are spacer members 36,37, preferably designed as seal members.

In the outlet area of the calibrating tool 33, the extruded article 6emerges without a large interspace into the cooling device 4, which canif necessary also serve as a calibrating device and at that point isthen cooled by the cooling devices known from prior art. This can bebrought about either by previously known water baths or spray baths orsimilar known arrangements. Preferably, calibration of the article 6 bymeans of the calibrating plates 10 indicated in the area of the coolingdevice 4, is carried out in this cooling device 4, as can be seen fromthe book by Michaelis or other publications in prior art, e.g. DE 195 04981 A1, EP0 659 536A2 and EP0 659 537 A2 or U.S. Pat. No. 3,473,194 A orDE 19 23 490 A, DE 22 39 746 A and EP 0 487 778 B1.

By means of using the spacer members 28 and 30,36 and 37, cavities 38 to41 surrounding the article 6 are provided between the extruder tool 8and the individual calibrating tools 24 and 31 to 33. These cavities 38to 41 are connected to lines 42 to 45, via which these cavities 38 to 41can be evacuated to a low pressure beneath the environmental pressure,i.e. air pressure. For this purpose the individual lines 42 to 45 can berespectively connected with their own vacuum generator 46 or a vacuumgenerator 46 common to all cavities 38 to 41. In the latter case, if acommon vacuum generator 46 is used for all cavities 38 to 41,low-pressure regulating units 47 can be located between it and theindividual cavities 38 to 41, so that for example the individualcavities 38 to 41 are evacuated to a more intense vacuum as the distancefrom the nozzle lip 27 increases. In order to enable compaction of atleast one surface 48 of the article 6 during passage of the article 6through the calibrating device 9, the calibrating tools 24 and 31 to 33are cooled.

For this reason, as FIG. 2 shows, they are provided with a cooling duct49, through which a temperature treatment means 50 can be passed. Thetemperature treatment means 50 for this purpose is passed by acirculating pump 51 to the cooling duct 49 via an inlet 52. Thetemperature treatment means 50, heated by cooling of the article,emerges again from the calibrating tool 24 at an outlet 53. Thetemperature treatment means 50 emerging from the outlet 53 can,particularly when a closed temperature treatment system is involved, becooled to the desired temperature and passed to a tank 55 for thetemperature treatment means 50. The quantity of temperature treatmentmeans 50 passed by the circulating pump 51 through the cooling duct 49can be produced, by means of measurement detectors 56,57, e.g. fordetermining pressure and/or temperature of the temperature treatmentmeans 50 with reference to the temperature difference and/or pressuredifference in the feed and return line for the temperature treatmentmeans 50, for which purpose the measurement detectors 57 can beconnected by a control device 58 to the circulating pump 51. Supply ofthe further calibrating tools 31 to 33 with a temperature treatmentmeans 50 is possible via the central circulating pump 51 or can also beprovided for each of the calibrating tools 24,31 to 33 via its owncirculating pump 51 with a closed or open circulating system for thetemperature treatment means 50. For the case where only one centralcirculating pump 51 is provided, with reference to the followingillustrations, the connection of the individual cooling ducts 49 isshown through the cavities 38 to 41. Thus the temperature of thetemperature treatment means 50 can be less than 40° C., but preferably20° C.

The spacer member 30, which seals the cavity 39 around the article 6from the surrounding air or the external air, is shown in particular inFIG. 2. This spacer member 30 in the present case is formed by aninflatable hollow seal profile 59 with a hollow chamber. Therefore thehollow chamber of this hollow seal profile 59 communicates via apressure line 60 to a pressure supply 61, such for example as a sourceof compressed air, a pressurised fluid such for example as water, oil orother preferably incompressible media, which ensures even with the lowpressure obtaining in the cavity 39, an air-tight seal with afluctuating distance 29. These alterations in distance can be requiredby the heat expansions of the material of the calibrating tools 24,31 to33 occurring due to temperature alterations, or to differing pressureconditions in the area of the individual cavities 38 to 41. Theindividual spacer members 30,36,37 or the hollow seal profile 59 form asurrounding seal device in the area of the cavities 38 to 41 between thearticle 6 and the external air or environmental air, and are preferablyformed to be of low heat conductivity, and/or elastically deformable.

Naturally, the spacer member 28 may also be formed by a welded hollowchamber seal or by a seal of solid material such for example as spongerubber or polyurethane or the like.

The article 6 emerging out of the last calibrating tool 33 in theextrusion direction, arrow 7, can then enter either directly, ifnecessary by sealing from the environmental air, such as between theindividual calibrating tools 24, 31 to 33 through an end wall 62 intothe cooling device 4, or these can be located at a pre-settablelongitudinal spacing 63 in the extrusion direction, arrow 7, behind thelast calibrating tool 33.

While the calibrating tools 31 to 33 are aligned towards one another onthe calibrating table 20 or upon support units located thereon in termsof height and side, and with reference to the medial longitudinal axis64 of the article 6 are in a centred location, in the present case thecalibrating tool 24 is located displaceably on guide pillars 65,66 inthe extrusion direction, arrow 7, aligned to the medial longitudinalaxis 64 of the article 6, and projecting beyond the calibrating tool 31in the direction of the calibrating tool 24. The calibrating tool 24located in this way in the extrusion direction, arrow 7, in a floatingmanner on the guide pillars 65,66 can be positioned by displacing thecalibrating table 20 along the guide rail 22 in the direction of theextruder 2, so that a sealing closure of the cavities 38,39 from theenvironmental air is achieved via the spacer members 28,30. When thecalibrating tool 24 is secured on the calibrating tool 31, care shouldbe taken that the latter is at least axially movably mounted withrespect to the calibrating tool 31. The individual cavities 38 to 41 canalso be termed slots or air passages, which in these embodiments serveas vacuum slots for shaping the article 6.

As may further be seen in particular from FIG. 3 and schematicallyindicated therein, there may be interposed between a suction pipe 67from the cavity 38 or the line 42 to the vacuum generator 46 a separator68 with a subsequent catchment container 69. By virtue of the fact thatdirectly following the nozzle lip 27 a cavity 38 is provided underpartial vacuum, the article 6, particularly a whole profile, emergingfrom the nozzle lip 27, is inflated by the applied pressure of theenvironmental air in the interior of the hollow profile, i.e. airpressure, and receiving its final shape, is brought into a calibratingchamber 70, which is formed by mould surfaces 71 to 78, FIG. 2, andwhich serve to profile and calibrate the surface 48 of the article 6. Inthis additional squeezing procedure in which the material 12 of thearticle 6 has for contact still substantially its extrusion temperature,lubricant residues contained in the material 12 are expressed or flushedout.

These lubricant residues have previously been deposited in the slots orvacuum slots in the calibrating tools 24,31 to 33 and led to smearformation in the area of the surface 48 of the article 6.

By virtue of the fact that these are now precipitated or expressed in ahot, liquid form, particularly in the cavity 38 and if necessary also inthe cavity 39, they can be extracted simultaneously with the extractionof the air in order to maintain the vacuum in the cavities 38,39, can beseparated in the separator 68 by the air extracted by the vacuumgenerator 46 and can be collected in a catchment container 69 fordisposal or re-use.

In this respect it proves advantageous if the line 42 is led from thecavity 38 to the suction pipe 67 in the extrusion tool 8, which isheated and kept at a high temperature, as then the extracted residuescannot condense or solidify and thus can be perfectly extracted. It isin fact also possible to lead the line 43, as shown in the area of thecalibrating tool 31, in the latter, yet it is recommended in this caseif necessary, in order to avoid excessively intense cooling of thecomponents to be extracted due to the cooling of the calibrating tool 31by the temperature treatment means 50, to provide the line 43 ifnecessary opposite the calibrating tool 31 with a heat insulation or toheat it separately with an inserted heating spiral.

The form of procedure for manufacturing an article for its calibrationin direct conjunction with the nozzle lip 27 is now as follows:

The usually pulverulent or granular material 12 plasticised in theextruder 2 is plasticised by the squeezing and shearing procedures inthe region of the extruder worms of the extruder 2 with simultaneousapplication of heat energy, and is passed via various deflectiondistribution ducts and mixing and heat treatment zones of the nozzle lip2 in a mould roughly adapted to the cross-sectional shape of the article6 to be produced, into the area of the nozzle lip 27, and is shapedtherein to the desired cross-sectional shape of the article 6. In thiscase a cross-sectional surface of the nozzle lip 27, surrounded by theface edges of the external mould surfaces of the extrusion tool 8, is ofsuch dimensions that said nozzle lip is smaller than a cross-sectionalsurface surrounded by the mould surfaces 71 to 78 of the calibratingtool 24 immediately following the extrusion tool 8, in the entry area ofthe calibration tool 24. Shrinkage of the article 6 occurring duringcooling is likewise to be taken into account in establishing theindividual cross-sectional surfaces, starting from the nozzle lip 27 asfar as the outlet region from the calibrating device 9.

The article 6, plasticised and having no intrinsic rigidity, emergingfrom the nozzle lip 26, particularly in the case of hollow profiles,enters the cavity 38 and at that point is exposed to the vacuum appliedhere, which is built up by the vacuum generator 46, and due to thepressure effect of the air in the interior of the hollow profile, i.e.the normal outer air pressure, relative to the low pressure in thecavity 38, is normally inflated by an extent of 0.1 mm to 0.4 mm.Thereupon this expanded article runs into the calibrating chamber 70 ofthe first calibrating tool 24. By means of the intake of material as itruns into the calibrating chamber 70 and the shaping thereby achieved,or the lubricants and additives deposited during the last shaping beforeemergence of the article from the nozzle lip 27, lubricants andadditives deposited on the surface of the article 6 to be shaped arepassed by the vacuum applied in the cavity 38 with the extracted airthrough the line 42 of the suction pipe 67 located in the heatedextrusion tool 8, from which point they pass into the separator.

Immediately after entry into the calibrating chamber 70, the article 6is smoothed in the area of its surface 48 by means of the smoothcontinuous mould surfaces 71 to 78, and stabilised by the lowtemperature of the mould surfaces 71 to 78 by the cooling with the heattreatment means 50 in the desired cross-sectional shape by cooling ofthe material in the direction of the hardening or gasificationtemperature. By means of passing through the cavity 39 following thecalibrating tool 24, the outer surfaces or surfaces 48 of the article 6which have not yet sufficiently hardened are pressed outwards by theexcess pressure exerted from the interior of the article 6 in the caseof the hollow profile, in order thus to suppress or remove tensionsarising by means of the cooling already initiating by means of webs orthe like lying in the interior of the article 6. Thereafter the profileruns in this now final desired external form along a lengthy path 79from mould surfaces 71 to 78 which are smooth and continuous and notprovided with apertures or recesses, to the next cavity 40. During thisgentle, unaffected passage, the surface 48 of the article 6 is nowextremely intensively cooled due to the cooling of the calibrating tool31 with the heat treatment means 50, so that it becomes capable ofsupporting load at least in the uppermost edge zones of itscross-section. After a repeated expansion of the article 6 as it passesthrough the cavity 40, the article 6 again passes through the mouldsurfaces 71 to 78 of the calibrating tool 32 and thus covers a path 80,which roughly corresponds to the path 79. Thereafter, the article 6,rigidified to this extent in the region of its surface layer, can bepassed to the following cooling device 4 or to a further cavity 41 inwhich the profile is again subjected to reduced pressure, and a furthercalibrating tool 33 of this cooling device 4. The individual paths 79 to81, covered by the article 6 passing through the calibrating tools 24,31 to 33, also correspond to the individual lengths of the calibratingtools 24, 31 to 33 and thus also to the individual mould surfaces 71 to78.

In order to produce a perfect surface of such articles 6, it has provedadvantageous if the paths 79,80 and thus the length of the mouldsurfaces 71 to 78 at least of the calibrating tools 31 to 33, comes toabout 200 mm. A path 81 and thus a length of the mould surfaces 71 to 78of the calibrating tool 24 on the other hand can come to only afraction, e.g. between 10% and 50% of the path 79, 80 of the calibratingtools 31 to 33. Preferred is a path 81 for the calibrating tool 24 ofbetween 20 mm and 70 mm, e.g. 30 mm, and a path 79,80 for thecalibrating tools 31 to 33 of between 200 mm and 250 mm, preferably 235mm.

Depending on the wall thickness of the article 6 or of the requiredfreedom from tension, two or even more calibrating tools 31 to 33 can bedisposed in succession in the extrusion direction in order to calibratean article 6.

In order to take account of the contraction of the article 6 during itscontinuous passage through the calibrating device 9, a distance 82between mould surfaces facing one another 77 and 73 or 75 and 77 or 71and 77 or mould surfaces 72 and 74 or 76 and 78 can be smaller withincreasing spacing of the calibrating tools 24 and 31 to 33 from theextrusion tool 8.

In order to maintain a minimum distance 29 or a minimum spacing 34,35between the various cavities 38 to 41, it can prove advantageous aboveall in the case of elastically deformable spacing members 28,30 in theextrusion direction, arrow 7, and particularly in the case of inflatableseal devices or seal devices of elastomers, to provide end stops 83,which ensure minimum distances or spacings.

FIG. 4 shows an arrangement in which each of the individual calibratingtools 24 and 31 to 33 is connected with its own coolant supply, i.e. itsown tank 84 and a circulating pump 51. Control of the supply of heattreatment means to the individual calibrating tools 24, 31 to 33 iseffected via a control device 58 and through control valves 85 orindividual intermediate pumps.

It may further be seen from this Figure that the low pressure in the twocavities 38,39 between the extrusion tool 8 and the calibrating tool 24immediately following it in the extrusion direction, arrow 7, or thenext calibrating tool 31 after this in sequence, is built up by its ownvacuum generator 46, which is preceded by a separator 68. Then, asalready described with reference to FIGS. 1 to 3, lubricants andadditives occurring in these areas can be removed from the surface areaof the workpiece 6. As is clearly seen from this view, a path 81 of thecalibrating tool 24 or of the mould surfaces 71 to 78 is smaller than70%, preferably smaller than 30% of the lengths of the paths 79,80 ofthe calibrating tools 31 to 33 or their mould surfaces 71 to 78. Invarious cases of application it may even prove advantageous if the path81 of the calibrating tool 24 comes to only about 15% of the paths 79,80of the calibrating tools 31,32. The paths 79 to 81 can however alsopreferably come to a multiple, e.g. 7 to 30 times, preferably 20 times,the distance 29 or the spacing 34,35.

A preferred length of the path 81 comes to 30 mm, while the paths 79,80come to 235 mm and the distance 29 and the spacings 34,35 come toroughly between 1 mm and 15 mm. In this connection it can also proveadvantageous if the length of the mould surfaces 71 to 78 of thecalibrating tools in the extrusion direction, arrow 7, i.e. the paths 79to 81, increases with the increasing spacing of the calibrating tool 31to 33 from the extrusion tool 8.

As is also shown schematically by way of example in FIG. 4, it isnaturally possible for the heat treatment means 50 to be passed not onlythrough a calibrating tool 24,31 to 33, but through a plurality of thesecalibrating tools, the heat treatment means 50 then being fed into oneof the calibrating tools 24,31 to 33 and being removed from anothercalibrating tool 24,31 to 33 to a heat-exchanger 54 and the tank 55. Thecontinued passage of the heat treatment means 50 from one calibratingtool to another in the extrusion direction, arrow 7, can be carried out,as shown on a larger scale schematically in FIG. 3, in that, in acooling duct 86, heat treatment means 50 is transferred via bores 89aligned concentrically and vertically to the end faces 87 and 88 facingone another of the calibrating tools 31,32. In order to seal thetransition, so that the latter permits a relative movement at all timeswith a sealed further passage of the heat treatment means 50, the twobores 89 are connected to a transition sleeve 90, which is inserted witha press fit into the bores 89 or transition bores with a larger diameterIf the press or force fit is insufficient to provide a seal on the basisof the relative movement with respect to temperature alterations betweenthe calibrating tools 31,32, a seal of the transition sleeve 90 can alsobe provided by O-rings 91 or the like in the individual calibratingtools 31,32.

In FIG. 5 a portion of the transition zone between the extrusion tool 8and the first calibrating tool 24 following it in the extrusiondirection, arrow 7, is shown on a larger scale. Located between theextrusion tool 8 and the calibrating tool 24 is a cavity 38. A guideplate 92 projects into this cavity 38 from the side relating to theextrusion tool 8. Between this guide plate 92 and the calibrating tool24 a feed duct 93 for a preferably liquid flushing agent 94 is formed,which is connected via a transverse duct 95 or inlet to a conveyor line96, which is for example acted on by a flushing agent pump 97. A suctionline 98 in the extrusion tool 8 is connected on the side facing thecavity 38 via a connection cavity 99 with the cavity 38. On the sidefacing away from the extrusion tool 8, the suction pipe 98 is connectedvia an inward suction pump 100 to a vacuum pump 101 with an interposedregenerating device 102 for the flushing agent 94, in which the residualmaterials, such as lubricants, additives or the like, which have beenflushed out by the flushing agent 94, and which are expressed or washedout or diffused out in the cavity 38 from the surface 48, are separated.The flushing agent pump 97, the vacuum pump 101 and the regeneratingdevice 102 with the feed and suction pipes 96,100 associated therewith,represent a supply system located outside the shaping device 3.

Naturally it is also possible in the construction described above toform any other cavity 39 to 41 in such a form that removal of anyresidues such as lubricants and additives and the like, from the surface48 of the article 6 is made possible.

In addition, as shown schematically, the feed duct 93 can be separatedby an insulating member 103 from the calibrating tool 24. By means ofdisposing the conveyor line 96 and the transverse duct 95 predominantlyin the heated extrusion tool 8, the flushing agent 94 fed in by theflushing agent pump 97 is heated, and at that point passes into theregion of the surface 48 of the article 6 which is continually movingpast, and with sufficient inflow pressure or high extraction power, canflush off lubricants and other additive materials contained on thesurface. In this respect the flow direction of the flushing agent 94 isselected to be contrary to the extrusion direction, arrow 7. Thisemulsion comprising the substances flushed out with the flushing agent94 can be removed in common with the air extracted to form a vacuum, inorder to shape the article 6 via the vacuum pump 101, through thesuction pipe 100, and can be separated in a regenerating device 102. Byvirtue of the fact that the connecting cavity 99 and the suction pipe 98are likewise disposed in the heated extrusion tool 8, these lubricantadditives and other material additives cannot be deposited in the lines,but are properly removed.

The design of the further cavities 39 to 41 and their possibleevacuation via the lines 43 to 45, in conjunction with the suction pipe67, can be effected in accordance with the description in the precedingFigures.

By means of a corresponding shaping of the nozzle lip 27 and of thecalibrating chamber 70, a corresponding build-up of the material 12 forthe article 6, or an additional squeezing of the material in the cavity38 can also be provided in a forced manner, so that the removal of thelubricants and other additives, which normally diffuse out on thesurface 48, is reinforced or effected in an automatic manner. It ishowever also possible to use the flushing agent 94 in a gaseous form andthus likewise to ensure removal of the lubricants and additives.

FIG. 6 shows a variant construction of a calibrating device 9, in whichonly three calibrating tools 24,31 and 32 are located in connection tothe extrusion tool 8. The extraction pipe for producing a vacuum in thecavity 39 between the calibrating tool 24 and 31 is in this case locatedin the cross-sectional area of the calibrating tool 24. The line 42 forproducing a vacuum in the cavity 38 can be located instead of thearrangement in the extrusion tool 8, as shown in dotted lines, in thecalibrating tool 24, so that the lines 42 and 43 are connected via acommon extraction line 104 with their vacuum generator 46, as alreadyillustrated and described in detail with reference to the precedingembodiments.

If the cavity 38 is connected via the line 42 in the extrusion tool 8 toa vacuum generator 46, it is for example also possible to apply reducedpressure to the two cavities 39 and 40, which are disposed on eitherside of the calibrating tool 31, via a central extractor line 104, asshown in dotted lines.

In this way, above all in the case of an arrangement of a plurality ofcalibrating tools disposed in succession, it is only necessary toproduce corresponding connecting ducts in order to build up a vacuum inthe cavities 38 to 41 in every second one.

FIG. 7 shows schematically that the cavities 38 to 41 between thecalibrating tools 24,31 to 33 can be sealed by rigid seals, for examplecopper or ceramic seals. This schematic view also shows that in thecalibrating tool 33 most remote from the extrusion tool 8, there arelocated one after the other at least over a portion of the length of themould surfaces 71 to 78 or of a path 105 of this calibrating tool 33,vacuum slots 106 or air passages in the extrusion direction, arrow 7.The individual vacuum slots 106 or air passages are connected via asuction pipe 67 to a vacuum generator 46 which is shown schematically.Such a design is above all recommended for workpieces which are providedwith a plurality of cross-webs lying in the cavity, in order to preventthe work piece from contracting in an uncontrolled manner and thuslosing its dimensional stability after emerging from the lastcalibrating tool 33.

It is advantageous in this respect that, due to the length of thepreceding smooth continuous mould surfaces 71 to 78 in the calibratingtools 24,31 to 33, and the extensive cooling of the surface 48 of thearticle 6, scarcely any further residues of lubricants or additives areseparated at the surface 48 of the article 6, so that the surfacequality of the article 6 in this area is not disadvantageouslyinfluenced and in addition blockage of these vacuum slots 106 by suchsolvent residues is avoided.

FIG. 8 again shows a calibrating tool 31 of the calibrating device 9 inan end view similar to FIG. 2, for which reason the same referencenumbers are used for identical parts.

The calibrating tool 31 shown in FIG. 8 differs from that shown in FIG.2 in that, for a small portion of the surface 48, particularly in thearea of a web 107 projecting over the outer peripheral surface of thearticle 6, particularly in a mould surface 109 facing its end surface108, a vacuum slot 110 or air passage is disposed, which can beconnected via a connecting duct 111 or a suction pipe 67 to a vacuumgenerator 46. This vacuum slot 110 can now be disposed over only apartial area of the path 79 of the mould surfaces 71 to 78, or aplurality of such vacuum slots 110 or air passages can be disposedbehind one another in the longitudinal direction of the path 79.

It is however also possible, instead of the shown arrangement, in whichthe vacuum slot 110 extends parallel to the extrusion direction, arrow7, for this vacuum slot 110 or a plurality of vacuum slots 110 disposedin succession over the mould surface 109 in the extrusion direction,arrow 7, to extend obliquely to the extrusion direction, arrow 7. Thearrangement of such small vacuum slots 110, above all in the area ofunstable thin projections, also enables in the area of these thinprojections Or smaller grooves, exact maintenance of the desired outerdimensions and complete shaping of these outer areas of the article 6.As the proportion of the surface of such projections or grooves or thelike is usually very small, i.e. lies below 10% of the overall surfaceof the article 6 or of the individual mould surfaces 71 to 78, this hasno disadvantageous influence on the quality of processing of the article6 over the remaining area.

In this embodiment it also proves advantageous if the cooling ducts 49extend parallel to the extrusion direction, arrow 7, through thecalibrating tools 31 to 33. It is also advantageous if the through-flowof the heat treatment agent 50 is contrary to the extrusion direction,arrow 7.

Naturally the individual embodiments described above and the variantsand differing constructions shown in these embodiments can each inthemselves form independent solutions according to the invention, andmay be combined with one another at will. This preferably relates to thearrangement of the calibrating tool 24 in conjunction with the extrusiontool 8 and of the individual calibrating tools 31 to 33 with oneanother.

Above all, the individual constructions shown in FIGS. 1;2,3;4;5;6;7,8can form the subject-matter of independent solutions according to theinvention. The objects and solutions according to the invention relatingto this are to be seen from the detailed descriptions of these Figures.

What is claimed is:
 1. A shaping deice for an extrusion system,comprising: a calibrating device having a plural of calibrating toolsarranged one after another along an extrusion direction in which anextruded article travels through the calibrating device, eachcalibrating tool having an upstream end face and a downstream end faceand mould surfaces extending between the upstream and downs end facesfor contacting outer surfaces of the extruded article passing throughthe calibrating tool, each calibrating tool further including coolingducts for passage of a heat-treatment agent therethrough; and at leastone seal device disposed between the downstream end face of at least onecalibrating tool and the up end face of an immediately succeedingcalibrating tool, the seal device being structured and arranged tomaintain a space in the extrusion direction between the respective endfaces between which the seal device is disposed so as to create a cavitysurrounding the extruded article that is closed off from environmentalpressure outside the calibrating device, whereby said cavity can beevacuated to a reduced pressure relative to said environmental pressure.2. The shaping device of claim 1, wherein a length of the mould surfacesof each calibrating tool in the extrusion direction is at least seventimes a length of said space between the end faces of adjacentcalibrating tools.
 3. The shaping device of claim 1, wherein eachcalibrating tool includes a passage therethrough opening into one of thecavities defined between the calibrating tool and an adjacent one of thecalibrating tools, whereby each cavity is evacuated to said reducedpressure.
 4. The shaping device of claim 3, further comprising a vacuumgenerator connected to the passage of each calibrating tool.
 5. Theshaping device of claim 4, further comprising a separator disposedbetween the vacuum generator and the passages of the calibrating toolsfor separating liquid lubricant that enters the cavities and issuctioned through the passages by the vacuum generator.
 6. The shapingdevice of claim 1, wherein a first one of the calibrating tools and animmediately succeeding second one of the calibrating tools in theextrusion direction are connected by members that allow said first andsecond calibrating tools to be moved relative to each other in theextrusion direction.
 7. The shaping device of claim 1, wherein the atleast one seal device comprises an inflatable seal that is inflated bypressurization of the seal device by a fluid, and further comprising apressure supply system connected with the at least one seal device forinflating the seal device.
 8. The shaping device of claim 1, whereineach calibrating tool defines an opening delimited by the mould surfacesfor the passage of the extruded article therethrough, and wherein saidopening of each calibrating tool is larger than said opening of animmediately succeeding one of the calibrating tools.
 9. The shapingdevice of claim 1, wherein a last of the calibrating tools in theextrusion direction has at least one air passage that opens through oneof the mould surfaces of said last calibrating tool, and furthercomprising a vacuum generator connected with the at least one airpassage.
 10. The shaping device of claim 1, wherein a length of themould surfaces of each calibrating tool is greater than a length of themould surfaces of an immediately preceding one of the calibrating tools.11. A shaping device for an extrusion system, comprising: an extrusiontool having an end face; a calibrating device having a first calibratingtool spaced in an extrusion direction from the extrusion tool, the firstcalibrating tool having an upstream end face opposing the end face ofthe extrusion tool and having a downstream end face, the firstcalibrating tool further including cooling ducts for passage of aheat-treatment agent therethrough and mould surfaces extending betweenthe upstream and downstream end faces defining an opening through thefirst calibrating tool for passage of an extruded article therethrough;and a seal device disposed between the end face of the extrusion tooland the upstream end face of the first calibrating tool surrounding theextruded article so as to create a cavity around the extruded articlethat is closed off from environmental pressure existing outside theshaping device, and wherein the seal device maintains a space betweenthe end face of the extrusion tool and the upstream end face of thecalibrating tool in the extrusion direction such that the cavity isdelimited by said end face and the seal device.
 12. The shaping deviceof claim 11, further comprising a plurality of said calibrating toolsarranged one after another in the extrusion direction with a downstreamend face of each calibrating tool opposing an upstream end face of animmediately succeeding one of the calibrating tools, and furthercomprising a seal device disposed between the downstream end face of atleast one calibrating tool and the upstream end face of the immediatelysucceeding calibrating tool, the seal device being structured andarranged to maintain a space in the extrusion direction between therespective end faces of the calibrating tools between which the sealdevice is disposed so as to create a cavity surrounding the exudedarticle that is closed off from environmental pressure outside theshaping device.
 13. The shaping device of claim 11, wherein the sealdevice is an inflatable seal, and further comprising a pressure supplysystem connected with the seal device for inflating the seal device. 14.The shaping device of claim 11, further comprising a vacuum generator,and a line connected between the vacuum generator and the cavity betweenthe extrusion tool and the first calibrating tool, said line beingformed at least partially in the extrusion tool.
 15. The shaping deviceof claim 14, wherein the extrusion tool further includes a slot openinginto the cavity for supplying a flushing agent into the cavity, andfurther comprising a supply system for supplying the flushing agentthrough said slot into the cavity, the supply system being locatedoutside the shaping device.
 16. The shaping device of claim 11, whereinthe seal device has a low heat conductivity and is elasticallydeformable.